Power module capable of resisting junction temperature fluctuation and power device

Abstract

The present application provides a power device and a power module. The power module comprises a phase change module and a chip which are stacked; the phase change module comprises an accommodating frame and a phase change material; the accommodating frame comprises at least two accommodating cavities; the at least two accommodating cavities are sequentially arranged in a direction facing away from the surface of the chip; the phase change material is arranged in the at least two accommodating cavities; the at least two accommodating cavities comprise a first accommodating cavity and a second accommodating cavity; the distance between the first accommodating cavity and the surface of the chip is smaller than the distance between the second accommodating cavity and the surface of the chip; and the phase change point of the phase change material in the first accommodating cavity is higher than that of the phase change material in the second accommodating cavity. The solution utilizes the distribution of temperature under the working conditions of the chip, so that phase change occurs in the phase change materials in the accommodating cavities having different distances from the surface of the chip, the heat absorption or energy storage effect is improved, and the function of junction temperature fluctuation resistance of the power module is enhanced.

Description

A power module and power device resistant to junction temperature fluctuations Technical Field

[0001] The present application relates to the field of electronic power technology, and in particular to a power module and power device that are resistant to junction temperature fluctuations. Background Art

[0002] In recent years, green energy has been rapidly developing and has become a key solution to the energy crisis. Power modules, as core components of green energy, have been widely used. As the output power of power conversion equipment rapidly increases, transient junction temperature fluctuations are also increasing. Due to the different thermal expansion coefficients of the various layers of material in the power modules of power conversion equipment, junction temperature fluctuations can lead to problems such as solder fatigue and bond wire shedding over long periods of operation, ultimately causing module failure and reliability issues. Therefore, current requirements for power modules' ability to withstand transient junction temperature fluctuations under overload conditions are further increased.

[0003] Phase change material (PCM) refers to a substance that changes state while maintaining constant temperature and can provide latent heat. The process by which a PCM transitions between solid, liquid, and gaseous states is called a phase change, during which the material absorbs or releases a significant amount of latent heat. The absorption or release of heat during a phase change by a PCM is called latent heat storage, and it offers the advantages of high energy storage density, constant temperature for storage and release, and recyclability. Therefore, PCMs can be used in power modules to help address the issue of fluctuating junction temperatures.

[0004] Summary of the Invention

[0005] This application provides a power module and power device that are resistant to junction temperature fluctuations. This application introduces phase change material into the power module and redesigns and optimizes the structure of the power module, effectively suppressing junction temperature fluctuations throughout the power module and improving its heat dissipation performance. Adding phase change material near the chip effectively increases the equivalent thermal capacity of the power module. This increase in thermal capacity effectively reduces chip junction temperature fluctuations and improves the temperature uniformity of the power module. In the present application, a containing frame is set at the surface position of the chip of the power module, and a plurality of containing cavities are set in the containing frame. Each containing cavity is filled with phase change material. Since the distance between each containing cavity and the chip is not equal, according to the temperature distribution of the chip during operation, the temperature will be lower the farther away from the chip. Therefore, the containing cavity closer to the chip is filled with phase change material with a high phase change point, and the containing cavity farther away from the chip is filled with phase change material with a low phase change point. The characteristics of different phase change points can be fully utilized. When the chip is overloaded, the phase change materials in each containing cavity can absorb or store heat through phase change, thereby maximizing the thermal capacity of the power module, effectively reducing the junction temperature fluctuation of the chip, and improving the temperature uniformity effect of the power module.

[0006] To this end, the embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a power module. The power module comprises: a phase change module and a chip, wherein the phase change module and the chip are stacked; the phase change module comprises a containing frame and a phase change material; the containing frame comprises at least two containing cavities, wherein the at least two containing cavities are sequentially arranged in a direction away from the first surface of the chip, and the phase change material is arranged in the at least two containing cavities; the at least two containing cavities comprise a first containing cavity and a second containing cavity, wherein the distance between the first containing cavity and the chip is smaller than the distance between the second containing cavity and the chip, and the phase change point of the phase change material in the first containing cavity is higher than the phase change point of the phase change material in the second containing cavity, wherein the first surface of the chip is perpendicular to the thickness direction of the power module.

[0008] It is understandable that according to the thermal imaging analysis of the chip, as the distance from the chip surface increases, the temperature around the chip gradually decreases. In order to fully utilize the phase change characteristics of the phase change material, a layered containment frame is used in this application, and phase change materials with different phase change points are used in different containment cavities. Among them, the distance between the containment cavity and the chip refers to the distance between the geometric center of the containment cavity and the geometric center of the chip, and can also be the distance between the geometric center of a containment wall of the containment cavity and the geometric center of a surface of the chip. For the calculation of the distance between different containment cavities and chips, it should be the distance between each containment cavity and the same surface of the chip, and the relative position of the containment wall in each containment cavity is the same. Specifically, a phase change material with a high phase change point is set in the containment cavity close to the chip, and a phase change material with a low phase change point is set in the containment cavity far from the chip, so that the phase change points of the phase change materials in each containment cavity show the characteristics of a gradient distribution, which is consistent with the temperature distribution trend around the chip. When the chip power is overloaded and the power consumption increases sharply, the phase change material in each cavity can reach the phase change point, thereby absorbing or storing heat, thereby maximizing the thermal capacity of the power module, effectively reducing the chip junction temperature fluctuation, and improving the temperature uniformity of the power module.

[0009] In combination with the first aspect, in a first possible embodiment, the at least two accommodating cavities are arranged in sequence along the thickness direction of the power module, and the plane where each of the accommodating cavities is located is parallel to the first surface of the chip, wherein the plane where the accommodating cavity is located is the plane where the surface of the accommodating cavity that is perpendicular to the thickness direction of the power module is located. It can be understood that different accommodating cavities are parallel to each other and are arranged in sequence in a direction away from the surface of the chip. This distribution of accommodating cavities is roughly the same as the distribution trend of the temperature around the chip in the horizontal direction, which is helpful for setting phase change materials with different phase change points. The horizontal direction refers to the direction parallel to the surface of the chip in the thickness direction of the power module.

[0010] In combination with the first aspect, in a second possible embodiment, the at least two accommodating cavities are arranged in sequence along the first direction, and the plane where each of the accommodating cavities is located is perpendicular to the first surface of the chip, and the first direction is perpendicular to the thickness direction of the power module, wherein the plane where the accommodating cavities are located is the plane where the surface of the accommodating cavities that is perpendicular to the first direction is located. It can be understood that different accommodating cavities are parallel to each other and are perpendicular to the surface of the chip. This distribution of accommodating cavities is roughly the same as the distribution trend of the temperature around the chip in the vertical direction, which is helpful for setting phase change materials with different phase change points. Among them, the vertical direction refers to the direction perpendicular to the surface of the chip in the thickness direction of the power module.

[0011] In conjunction with the first aspect, in a third possible implementation, the at least two cavities are arranged sequentially along a first direction, with each cavity located in a plane perpendicular to the surface of the chip. Each of the at least two cavities is annular and arranged sequentially from the center of the chip toward the edge of the chip. It will be understood that the temperature at locations with the same distance from the chip's geometric center should be roughly the same, and the distribution pattern of the annular cavities is roughly the same as the temperature distribution trend around the chip in a direction extending outward from the chip's geometric center. The different cavities are nested within each other, which facilitates the placement of phase change materials with different phase transition points.

[0012] In conjunction with the first aspect, in a fourth possible implementation, each of the at least two accommodating cavities is hemispherically arc-shaped and is arranged sequentially from the center of the chip surface toward the direction away from the chip. It will be understood that the temperature at locations at the same distance from the chip should be roughly the same, and the isotherms around the chip roughly form a hemispherical arc. The distribution pattern of the hemispherical arc-shaped accommodating cavities is roughly the same as the temperature distribution trend around the chip. The different accommodating cavities are nested within each other, which facilitates the placement of phase change materials with different phase transition points.

[0013] In conjunction with the first aspect, in a fifth possible implementation, the phase change module includes a first phase change module, the first phase change module is disposed on a first surface of the chip, the second surface of the chip is used to dispose a first heat sink, and the first surface and the second surface are disposed opposite each other. It will be appreciated that the phase change material in the phase change module can increase thermal resistance, and therefore, the phase change material can be reduced in the heat dissipation path, or the phase change module can be disposed in a non-heat dissipation path. The phase change module and the heat sink are respectively disposed on two opposing surfaces of the chip in the thickness direction of the power module, thereby ensuring effective heat dissipation of the power module.

[0014] In conjunction with the first aspect, in a sixth possible embodiment, the housing frame of the first phase change module includes a flow passage, the flow passage being used to provide a path for current in the chip. The flow passage is disposed on a side of the housing frame of the first phase change module that is close to the chip, and the content of phase change material per unit volume in the flow passage is less than the content of phase change material per unit volume in other portions of the housing frame of the first phase change module. It is understandable that the phase change material in the first phase change module generally has poor conductivity, which is not conducive to the conduction of current. Therefore, the provision of phase change material is reduced in the flow passage where current flows, thereby improving the conductivity of the phase change module.

[0015] In combination with the first aspect, in a seventh possible implementation, no phase change material is provided in the flow-through portion. It is understandable that not providing the phase change material in the flow-through portion can maximize the conductivity of the phase change module.

[0016] In conjunction with the first aspect, in an eighth possible implementation, the phase change module includes a second phase change module, and the second phase change module is disposed between the chip and the first heat sink. It will be appreciated that disposing the phase change module between the chip and the heat sink can also reduce chip junction temperature fluctuations and improve temperature uniformity of the power module.

[0017] In conjunction with the first aspect, in a ninth possible embodiment, the housing frame of the second phase change module includes a first heat dissipation portion and a first phase change portion. The first phase change portion is disposed around the first heat dissipation portion, and a projection of the first heat dissipation portion on the chip thickness overlaps with the first surface of the chip. The content of phase change material per unit volume in the first heat dissipation portion is less than the content of phase change material per unit volume in the first phase change portion. It will be understood that the first heat dissipation portion is located in the heat dissipation path of the power module, and the phase change material in the phase change module can increase thermal resistance. Therefore, reducing the amount of phase change material in the heat dissipation path can ensure effective heat dissipation of the power module.

[0018] In conjunction with the first aspect, in a tenth possible implementation, no phase change material is provided in the first heat dissipation portion. It is understandable that not providing the first heat dissipation portion with a phase change material can maximize the heat dissipation efficiency of the power module.

[0019] In conjunction with the first aspect, in an eleventh possible embodiment, a second heat sink is disposed on a surface of the first phase change module facing away from the chip. The housing frame of the first phase change module includes a second heat sink and a second phase change portion. The second phase change portion is disposed around the second heat sink, and a projection of the second heat sink onto the chip thickness overlaps the first surface of the chip. The content of phase change material per unit volume in the second heat sink is less than the content of phase change material per unit volume in the second phase change portion. It will be appreciated that the second heat sink is located on the heat dissipation path of the power module, and the phase change material in the phase change module can increase thermal resistance. Therefore, reducing the amount of phase change material in the heat dissipation path can ensure effective heat dissipation of the power module.

[0020] In combination with the first aspect, in a twelfth possible implementation, no phase change material is provided in the second heat dissipation portion. It is understandable that not providing the second heat dissipation portion with phase change material can maximize the heat dissipation efficiency of the power module.

[0021] In conjunction with the first aspect, in a thirteenth possible implementation, the projection of the first phase change module in the thickness direction of the power module covers the first surface of the chip. It will be appreciated that the projected area of ​​the first phase change module is larger than the area of ​​the first surface of the chip, allowing more phase change material to be accommodated in the accommodating cavity, thereby increasing the content of the phase change material in the power module and further improving the thermal capacity of the power module.

[0022] In combination with the first aspect, in a fourteenth possible implementation, the power module includes a metal-clad substrate, which is stacked with the chip and in contact with the surface of the chip; or, the metal-clad substrate is arranged on the side of the phase change module away from the chip. Generally, the metal-clad substrate is a copper-clad ceramic substrate (Direct Bond Copper, DBC), an active metal brazed copper substrate (Active metal brazed copper, AMB, such as Al2O3-AMB, Si3N4-AMB or AlN-AMB) or an insulated metal substrate (Insulated metal substrate, IMS), etc. Exemplarily, in order to further improve the power density, the metal-clad substrate can be formed of AlN-DBC, Si3N4-AMB or AlN-AMB with high thermal conductivity, which is not limited here.

[0023] In combination with the first aspect, in a fifteenth possible implementation, the phase change frame is a metal frame or a diamond frame, and the phase change material is any one or more of a single metal, an alloy, an organic matter, and an inorganic salt.

[0024] In combination with the first aspect, in a sixteenth possible implementation, the power module further includes a plastic package, the chip and the phase change module are arranged inside the plastic package, or the chip is arranged in the plastic package, and the phase change module is arranged outside the plastic package.

[0025] In combination with the first aspect, in a seventeenth possible implementation manner, the at least two accommodating cavities are interconnected.

[0026] In a second aspect, embodiments of the present application provide a power device, characterized in that the power device comprises: at least one power module and a circuit board as described in the first aspect, the at least one power module being disposed on the circuit board, and the at least one power module being used for AC / DC power conversion. It is understood that the power device includes the power module as described in the embodiment of the first aspect. Because the power module has excellent resistance to junction temperature fluctuations, it can still maintain a relatively uniform temperature of the chip during power overload, thereby improving the operating performance of the power device during power overload and enhancing stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the heat dissipation path of a current power module;

[0028] Figure 2 Cauer RC thermal network model of the power module;

[0029] 3A-3E are schematic diagrams of a power module structure provided in Example 1;

[0030] FIG3F is a schematic diagram of the three-dimensional structure of a phase change module in a power module provided in Example 1;

[0031] FIG4A is a schematic diagram of a power module structure provided in Example 2;

[0032] FIG4B is a schematic diagram of the three-dimensional structure of a phase change module in a power module provided in Example 2;

[0033] FIG5A is a schematic diagram of a power module structure provided in Example 3;

[0034] FIG5B is a schematic diagram of the three-dimensional structure of a phase change module in a power module provided in Example 3;

[0035] FIG6A is a schematic diagram of a power module structure provided in Example 4;

[0036] FIG6B is a schematic diagram of the three-dimensional structure of a phase change module in a power module provided in Example 4;

[0037] 7A-7C are schematic diagrams of a power module structure provided in Example 5;

[0038] 8A-8B are schematic diagrams of a power module structure provided in Example 6;

[0039] FIG8C is a schematic diagram of a power module structure provided in Example 7;

[0040] 9A-9B are schematic diagrams of a power module structure provided in Example 8;

[0041] FIG10 is a schematic diagram of a power module structure provided in Example 9;

[0042] FIG11 is a schematic diagram of a power module structure provided in the tenth embodiment.

[0043] Figure markings: Substrate-1, silicone grease-2, substrate connecting layer-3, chip connecting layer-4, plastic package-5, chip-30, chip-30', heat sink-40-41, metal-clad substrate-60, phase change frame-10, phase change frame-10', accommodating cavity-11-18, accommodating cavity-71-76, accommodating cavity-01-06, accommodating cavity-11'-13', accommodating cavity-71'-76', phase change material-21-28, phase change material-81-86, phase change material-91-96, phase change material-21'-23', phase change material-81'-86'. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0045] Power modules play a crucial role in power devices, serving as core components in applications ranging from new energy vehicles to smart photovoltaics. During operation, the chips within the power modules frequently switch between on and off states to convert AC / DC power. As the industry evolves towards higher voltages, power modules are also evolving towards higher voltages. Power modules frequently operate under overload conditions, such as during acceleration and deceleration in new energy electric vehicles and the start and stop of high-voltage power generation in smart photovoltaics. This results in junction temperature fluctuations within the power modules. Power modules are constructed from stacked and connected materials with significant differences in thermal expansion coefficients. Temperature fluctuations can cause thermal stress aging within the interconnect layers that connect the modules, leading to reliability issues such as solder fatigue and bond wire separation. Junction temperature fluctuations significantly impact module lifespan. Reducing junction temperature fluctuations in power modules is crucial for improving module reliability in applications where power levels fluctuate frequently.

[0046] The general structure of the power module is as shown in Figure 1. The chip 30 is soldered to the metal-clad substrate 60 through solder. The metal-clad substrate 60 is then soldered to the substrate 1 to form the internal package of the module, and is encapsulated by the plastic package 5. The power module and the heat sink 40 are connected by thermal grease 2. When the power module is working, the chip 30 will generate heat loss. The heat is transferred to the heat sink 40 through the metal-clad substrate 60, the substrate 1, and the silicone grease 2. The heat is dissipated by active or passive heat dissipation. Generally speaking, the junction temperature of the chip 30 in the power module does not exceed the maximum allowable temperature. According to the Cauer RC thermal network model of the power module, as shown in Figure 2, there are two ways to reduce the junction temperature fluctuation of the power module under power fluctuation conditions. One is to reduce the thermal resistance R on the heat dissipation path of the power module, and the other is to increase the internal heat capacity C of the power module.

[0047] Reducing thermal resistance in the heat dissipation path primarily involves reducing the thermal resistance of the contact materials between different components. For example, silver sintering is used to connect the module to the heat sink. This process technology is relatively mature and has been commercially adopted. Currently, industry research focuses on increasing the thermal capacitance of power modules and reducing junction temperature fluctuations.

[0048] The current mainstream approach to increasing heat capacity in heat dissipation paths is through the application of phase change materials (PCMs). Phase change materials (PCMs) absorb or release heat during phase transitions while maintaining a constant temperature. Their dQ / dT ratio is equivalent to infinity, meaning their equivalent heat capacity is infinite. Therefore, PCMs are highly valuable for increasing heat capacity. PCMs have been used in integrated circuits for thermal management applications such as heat sinks, but their long temperature response time limits their cooling effectiveness. To address this issue, a copper block with a specially designed structure is inserted between the chip and the DBC. The slots within the copper block are filled with PCM, leveraging the latent heat absorption properties of the PCM during its phase transition. However, this design typically results in only a portion of the PCM undergoing phase transition under overload conditions, failing to fully utilize the PCM's heat absorption properties. Therefore, a new power module structure is needed that allows the module to respond more quickly to changes in junction temperature during power fluctuations, reducing the magnitude of junction temperature fluctuations and improving power module reliability.

[0049] In response to the above problems, the present application provides a new type of power module and power device. The thermal map analysis of the chip in the working state shows that the closer to the chip, the higher the temperature, and the temperature around the chip shows a gradually decreasing distribution from the center of the chip to the direction away from the chip. In order to make full use of the distribution of chip temperature, a phase change frame is set near the chip, and multiple accommodating cavities are set at different distances from the chip in the phase change frame. Phase change materials with different phase change points are set in different accommodating cavities, so that phase change materials with different phase change points can all undergo phase change, thereby maximizing the utilization rate of the phase change material.

[0050] The first embodiment provided by the present application is shown in FIG3A . The first embodiment of the present application provides a power module, comprising a chip 30 and a phase change frame 10. The phase change frame 10 includes two cavities, specifically, a cavity 11 and a cavity 12. The cavities 11 and 12 are arranged in a direction away from the first surface of the chip 30. A phase change material 21 is disposed in the cavity 11, and a phase change material 22 is disposed in the cavity 12. The distance between the cavity 12 and the chip 30 is less than the distance between the cavity 11 and the chip 30. The phase change point of the phase change material 22 in the cavity 12 is higher than the phase change point of the phase change material 21 in the cavity 11. The phase change point of the phase change material 22 is equal to the temperature of the chip 30 at the cavity 12 under overload conditions, and the phase change point of the phase change material 21 is equal to the temperature of the chip 30 at the cavity 11 under overload conditions. Note: The term "equal" here includes approximately equal, not necessarily completely equal, such as a difference of 1%-10%. Through the above arrangement, when the chip 30 operates under overload conditions, both the phase change material 21 and the phase change material 22 can undergo phase change, which can absorb or store energy to the maximum extent, increase the heat capacity of the power module, and improve the power module's resistance to junction temperature fluctuations.

[0051] The accommodating cavity 11 and the accommodating cavity 12 are rectangular parallelepipeds with a certain height in the thickness direction of the power module. The surfaces of the accommodating cavity 11 and the accommodating cavity 12 in the thickness direction of the power module are parallel to the surface of the chip 30 in the thickness direction of the power module, wherein the plane where the accommodating cavity is located is the plane where the surface of the accommodating cavity in the thickness direction of the power module is located. In a feasible embodiment, the projections of the accommodating cavity 11 and the accommodating cavity 12 in the thickness direction of the power module cover the projection of the chip 30 in the thickness direction of the power module. This setting can increase the phase change area of ​​the phase change frame and improve the effect of resisting junction temperature fluctuations. Of course, the size of the phase change frame can also be set according to the junction temperature fluctuation of the chip. For chips with small junction temperature fluctuations, the setting of the phase change frame can be reduced so that the projection area of ​​the accommodating cavity 11 and the accommodating cavity 12 in the thickness direction of the power module is smaller than the projection area of ​​the chip 30 in the thickness direction of the power module.

[0052] In some feasible embodiments, the phase change frame 10 may include more than two accommodating cavities. As shown in FIG3B , the phase change frame 10 includes five accommodating cavities, each of which is provided with a phase change material having a different phase change point. Specifically, the accommodating cavity 11 is provided with a phase change material 21, the accommodating cavity 12 is provided with a phase change material 22, the accommodating cavity 13 is provided with a phase change material 23, the accommodating cavity 14 is provided with a phase change material 24, and the accommodating cavity 15 is provided with a phase change material 25. Among them, the distances between the accommodating cavity 11, the accommodating cavity 12, the accommodating cavity 13, the accommodating cavity 14, and the accommodating cavity 15 and the chip 30 decrease successively, while the phase change points of the phase change material 21, the phase change material 22, the phase change material 23, the phase change material 24, and the phase change material 25 increase successively. The specific settings of the phase change points of the phase change material 21, the phase change material 22, the phase change material 23, the phase change material 24, and the phase change material 25 can be set according to the temperature distribution of the chip 30 under overload conditions, so that the phase change materials in each accommodating cavity can undergo phase change, thereby maximizing the thermal capacity of the power module.

[0053] At the same time, different accommodating cavities can be connected or separated from each other, and the specific settings can be adjusted according to the application scenario. The material of the accommodating frame 10 can be metal or diamond. Diamond has a better heat dissipation effect, but it is more expensive. The frame material can be flexibly selected according to actual needs. The material of the phase change material can be any one or more of a single metal, an alloy, an organic substance, and an inorganic salt, and can be selected according to the temperature distribution of the chip 30 during actual working conditions.

[0054] In some feasible embodiments, based on the actual temperature distribution of the chip 30, the phase change points of the phase change materials in each accommodating cavity do not necessarily have to be different. As different phase change cavities are farther and farther away from the chip 30, it is sufficient as long as the phase change points of the corresponding phase change materials in the accommodating cavity show a gradually decreasing trend. As shown in FIG3C , the arrangement of the accommodating cavity is the same as in FIG3B , but the arrangement of the phase change materials is different. Specifically, the phase change points of the phase change materials 21, 22, and 23 are the same, the phase change points of the phase change materials 24 and 25 are the same, and the phase change points of the phase change materials 21, 22, and 23 are less than the phase change points of the phase change materials 24 and 25. Similarly, as shown in FIG3D , the arrangement of the accommodating cavity is the same as in FIG3B , but the arrangement of the phase change materials is different. Specifically, the phase change points of phase change material 21, phase change material 22, phase change material 23, and phase change material 24 are the same, the phase change point of phase change material 25 is different from the phase change points of the other four phase change materials, and the phase change points of phase change material 21, phase change material 22, phase change material 23, and phase change material 24 are less than the phase change point of phase change material 25. Furthermore, in some embodiments, as shown in FIG3E , the arrangement of the accommodating cavity is the same as that in FIG3B , but the arrangement of the phase change materials is different. Specifically, the phase change points of phase change material 21, phase change material 22, phase change material 23, phase change material 24, and phase change material 25 are the same, that is, the discrete arrangement of phase change materials with the same phase change point can also improve the utilization rate of the phase change material and further enhance the thermal capacity of the power module.

[0055] As shown in Figure 3F, which is a schematic diagram of the three-dimensional structure of the phase change frame, the accommodating cavity 11, the accommodating cavity 12, the accommodating cavity 13, the accommodating cavity 14 and the accommodating cavity 15 are rectangular prisms with a certain height in the thickness direction of the power module. The accommodating cavity 11, the accommodating cavity 12, the accommodating cavity 13, the accommodating cavity 14 and the accommodating cavity 15 are arranged in sequence along the thickness direction of the power module, and the surfaces of the accommodating cavity 11, the accommodating cavity 12, the accommodating cavity 13, the accommodating cavity 14 and the accommodating cavity 15 in the thickness direction of the power module are parallel to the surface of the chip 30 in the thickness direction of the power module.

[0056] In a second embodiment, as shown in FIG4A , the accommodating cavities in the phase change frame are spaced apart from each other, and the planes where the accommodating cavities are located are perpendicular to the surface of the chip 30 . The three-dimensional shape of the accommodating cavities is shown in FIG4B . The plane where the accommodating cavities are located is the plane where the surface of the accommodating cavities that is perpendicular to the first direction is located. The plane where the accommodating cavities are located is perpendicular to the surface of the chip 30 in the thickness direction of the power module and extends along the second direction. The first direction, the second direction and the thickness direction of the power module are perpendicular to each other.

[0057] The phase change frame 10 includes a housing chamber 11, a housing chamber 12, a housing chamber 13, a housing chamber 14, a housing chamber 15, a housing chamber 16, a housing chamber 17, and a housing chamber 18. The housing chamber 11 is symmetrically arranged with the housing chamber 18, the housing chamber 12 is symmetrically arranged with the housing chamber 17, the housing chamber 13 is symmetrically arranged with the housing chamber 16, and the housing chamber 14 is symmetrically arranged with the housing chamber 15. Symmetrical arrangement means that the distances between different housing chambers and the chip 30 are equal, and they are symmetrically arranged on both sides of the geometric center of the chip 30. The distances between the housing chambers 11 and 18, the housing chambers 12 and 17, the housing chambers 13 and 16, and the housing chambers 14 and 15 and the surface of the chip 30 decrease in sequence. Here, the distance to the chip 30 is the distance between the geometric center of each housing chamber or the geometric center of a housing wall and the geometric center of the surface of the chip 30.

[0058] Each accommodating cavity is provided with a phase-change material having a different phase transition point. Specifically, accommodating cavity 11 is provided with phase-change material 21, accommodating cavity 12 is provided with phase-change material 22, accommodating cavity 13 is provided with phase-change material 23, accommodating cavity 14 is provided with phase-change material 24, accommodating cavity 15 is provided with phase-change material 25, accommodating cavity 16 is provided with phase-change material 26, accommodating cavity 17 is provided with phase-change material 27, and accommodating cavity 18 is provided with phase-change material 28. Phase-change material 21 and phase-change material 28 have the same phase transition point, phase-change material 22 and phase-change material 27 have the same phase transition point, phase-change material 23 and phase-change material 26 have the same phase transition point, and phase-change material 24 and phase-change material 25 have the same phase transition point. The phase transition points of phase-change material 21 and phase-change material 28, phase-change material 22 and phase-change material 27, phase-change material 23 and phase-change material 26, and phase-change material 24 and phase-change material 25 increase in order. The specific settings of the phase change points of phase change material 21, phase change material 22, phase change material 23, phase change material 24, phase change material 25, phase change material 26, phase change material 27 and phase change material 28 can be set according to the temperature distribution of chip 30 under overload conditions, so that the phase change materials in each accommodating cavity can undergo phase change, thereby maximizing the thermal capacity of the power module.

[0059] In a third embodiment, as shown in Figures 5A-5B , the accommodating cavities in the phase change frame 10 are annular, three-dimensional structures arranged sequentially from the center of the chip 30 toward the edge of the chip 30. The sidewalls of each accommodating cavity lie on a plane perpendicular to the surface of the chip 30. The temperature at locations at the same distance from the chip 30 should be roughly the same. The distribution pattern of the annular accommodating cavities is roughly the same as the temperature distribution trend around the chip 30 in a direction extending outward from the geometric center of the chip 30 surface. The different accommodating cavities are nested within each other, as shown in Figures 5A-5B . The junctions between adjacent sidewalls of each accommodating cavity are right angles. Generally, the junctions between different accommodating cavities can also be arc-shaped.

[0060] Phase change frame 10 includes cavities 11, 12, and 13, wherein cavities 11, 12, and 13 are nested with each other. The four sidewalls of each of cavities 11, 12, and 13 are symmetrically arranged relative to the center of the surface of chip 30, and the planes on which the four sidewalls of each of cavities 11, 12, and 13 lie are perpendicular to the surface of chip 30 in the thickness direction of the power module. Cavities 11, 12, and 13 are each provided with phase change materials having different phase change points. Specifically, cavity 11 is provided with phase change material 21, cavity 12 is provided with phase change material 22, and cavity 13 is provided with phase change material 23. The distances of cavities 11, 12, and 13 from chip 30 decrease in sequence, while the phase change points of phase change materials 21, 22, and 23 increase in sequence. The specific settings of the phase change points of phase change material 21, phase change material 22, and phase change material 23 can be set according to the temperature distribution of chip 30 under overload conditions, so that the phase change materials in each accommodating cavity can undergo phase change, thereby maximizing the thermal capacity of the power module.

[0061] In a fourth embodiment, as shown in Figures 6A-6B, the accommodating cavities within the phase change frame 10 are hemispherical arc-shaped, arranged sequentially from the center of the chip 30 toward the edge of the chip 30. The different accommodating cavities are nested within each other, and each cavity opens toward the surface of the chip 30 along the thickness of the power module. The temperature at locations at the same distance from the chip 30 should be roughly the same. The distribution pattern of the hemispherical arc-shaped cavities is roughly the same as the temperature distribution trend around the chip 30, extending outward from the geometric center of the chip 30.

[0062] The phase change frame 10 includes a housing cavity 11, a housing cavity 12, a housing cavity 13, and a housing cavity 14, wherein the shapes of the housing cavities 11, 12, 13, and 14 are all hemispherical arcs and the various housing cavities are nested with each other. The cross-section of the plane where the surface of the chip 30 in the thickness direction of the power module is located is annular, and the center of each ring roughly coincides with the center of the surface of the chip 30. The housing cavities 11, 12, 13, and 14 are respectively provided with phase change materials with different phase change points. Specifically, the housing cavity 11 is provided with a phase change material 21, the housing cavity 12 is provided with a phase change material 22, the housing cavity 13 is provided with a phase change material 23, and the housing cavity 14 is provided with a phase change material 24. The distances between the arc-shaped walls of cavities 11, 12, 13, and 14 and chip 30 decrease in sequence, while the phase transition points of phase-change materials 21, 22, 23, and 24 increase in sequence. The temperatures at locations at the same distance from the surface of chip 30 should be roughly the same. The isotherms surrounding the chip roughly form a hemispherical arc. The distribution of the hemispherical arc-shaped cavities roughly mirrors the temperature distribution trend around the chip. The nesting of different cavities facilitates the placement of phase-change materials with different phase transition points, improving the utilization of the phase-change materials.

[0063] Embodiments 1 to 4 provide a detailed introduction to the shape and distribution of each accommodating cavity in the phase change frame 10. It is worth noting that the shape and distribution of the accommodating cavity in the phase change frame 10 are not limited to the above four cases. In order to further make the setting of the accommodating cavity consistent with the operating temperature distribution of the chip 30, the accommodating cavity can be further divided, and the accommodating cavity can be set to a grid shape, and the accommodating cavity can be further divided into multiple sub-accommodating cavities. For example, the accommodating cavity 11 in embodiment 2 is divided into multiple grid structures in the second direction and the thickness direction. The refined accommodating cavity can further set phase change materials with different phase change points to improve the utilization rate of the phase change material.

[0064] In the fifth embodiment, the power module generally requires cooperation with a heat sink to remove heat from the chip. As shown in FIG7A , a first heat sink 40 is provided on the second surface of the chip 30, and the phase change module includes a first phase change module. Because phase change materials have a poor heat dissipation effect, the placement of phase change materials in the heat dissipation path should be minimized. Therefore, the first phase change module is placed on the first surface of the chip 30, contacting the first surface of the chip 30, while the heat sink is placed on the second surface of the chip 30, opposite the first surface, to improve heat dissipation.

[0065] Generally, current flows along the first surface of the chip 30, so the current in the chip 30 will flow through the containment frame. However, the phase change material has poor conductivity. Therefore, to ensure that the containment frame 10 provides a more optimal current flow path for the chip 30, a flow passage is provided in the containment frame 10. The flow passage is used to provide a path for the current in the chip 30. The flow passage is provided on the side of the containment frame 10 of the phase change module that is closer to the chip. The content of phase change material per unit volume in the flow passage is less than the content of phase change material per unit volume in other parts of the containment frame 10. As shown in FIG7B , the containment frame 10 includes a containment cavity 11, a containment cavity 12, a containment cavity 13, a containment cavity 14, and a containment cavity 15. The flow passage is the approximate location of the containment cavity 14 and the containment cavity 15 in the containment frame 10. Regarding the height of the containment cavities, the height of the containment cavities 14 and 15 in the direction of the power module thickness is less than the height of the containment cavities 11, 12, and 13 in the direction of the power module thickness. The volumes of the accommodating chamber 14 and the accommodating chamber 15 are smaller than the volumes of the accommodating chamber 11, the accommodating chamber 12, and the accommodating chamber 13. Therefore, the content of the phase change material in the accommodating chamber 14 and the accommodating chamber 15 is smaller than the content of the phase change material in the accommodating chamber 11, the accommodating chamber 12, and the accommodating chamber 13. Furthermore, as shown in FIG7C , the accommodating frame 10 includes the accommodating chamber 11, the accommodating chamber 12, the accommodating chamber 13, and the accommodating chamber 14. Among them, the flow portion is the approximate position where the accommodating chamber 14 is located in the accommodating frame 10. No phase change material is provided in the accommodating chamber 14. In terms of the height setting of the accommodating chamber, the height of the accommodating chamber 14 in the thickness direction of the power module can be the same as or different from the height of other accommodating chambers. Furthermore, the accommodating chamber can also be not provided at the position of the accommodating chamber 14, so as to maximize the use of the conductive properties of the accommodating frame and improve the flow capacity of the flow portion.

[0066] In the sixth embodiment, as shown in FIG8A , when the power module needs to be matched with a heat sink, the phase change module further includes a second phase change module, which is arranged between the chip 30 and the first heat sink 40. Since the second phase change module is arranged on the heat dissipation path of the chip 30, and the phase change material will affect the heat transfer, it is best not to arrange phase change material on the heat dissipation path. The accommodating frame 10 of the second phase change module includes a first heat dissipation portion and a first phase change portion. The first phase change portion is arranged around the first heat dissipation portion, and the projection of the first heat dissipation portion on the thickness of the power module overlaps with the first surface of the chip 30; the content of the phase change material per unit volume in the first heat dissipation portion is less than the content of the phase change material per unit volume in the first phase change portion. Furthermore, no phase change material is arranged in the first heat dissipation portion.

[0067] The first phase change portion includes a housing cavity 71, a housing cavity 72, a housing cavity 73, a housing cavity 74, a housing cavity 75, and a housing cavity 76, wherein the plane in which the housing cavities 71, 72, 73, 74, 75, and 76 are located is parallel to the surface of the chip 30. The surface of the chip 30 may be the first surface or the second surface of the chip 30. The housing cavity 71 and the housing cavity 74 are arranged on the same plane, the housing cavity 72 and the housing cavity 75 are arranged on the same plane, and the housing cavity 73 and the housing cavity 76 are respectively arranged on the same plane. The phase change material in the housing cavity 71 and the housing cavity 74 has the same phase change point, the phase change material in the housing cavity 72 and the housing cavity 75 has the same phase change point, and the phase change material in the housing cavity 73 and the housing cavity 76 has the same phase change point. The phase change point of the phase change material can be set according to the operating temperature distribution of the chip 30.

[0068] In order to fully improve the thermal capacity of the power module, phase change modules can be set on both the first surface and the second surface of the chip 30. As shown in Figure 8B, the first phase change module is set on the first surface of the chip 30, and the second phase change module is set on the second surface of the chip 30. The setting of the accommodating cavity and the phase change material in the first phase change module can refer to the setting of the first phase change module in Figure 7A in Example 5, and the setting of the accommodating cavity and the phase change material in the second phase change module can refer to the setting of the second phase change module in Figure 8A in Example 6.

[0069] In a seventh embodiment, for a power module with double-sided heat dissipation, as shown in FIG8C , the phase change module includes a first phase change module and a second phase change module. The first phase change module is disposed on the first surface of the chip 30, and the second phase change module is disposed on the second surface of the chip 30. The side of the first phase change module facing away from the chip 30 is used to dispose the second heat sink 41, and the side of the second phase change module facing away from the chip 30 is used to dispose the first heat sink 40. The arrangement of the accommodating cavities and phase change materials in the first and second phase change modules can refer to the arrangement of the second phase change module in FIG8A of the seventh embodiment.

[0070] In some feasible embodiments, to increase the thermal capacity of the power module, the relative area between the phase change module and the chip 30 can be further increased so that the projection of the first phase change module or the second phase change module in the thickness direction of the power module covers the first surface of the chip 30. The arrangement of the accommodating cavity and the phase change material in the first phase change module or the second phase change module is not limited herein and can be the arrangement of any phase change module in Examples 1 to 6.

[0071] In an eighth embodiment, as shown in FIG9A , the power module further includes a metal-clad substrate 60 . The metal-clad substrate 60 can be disposed on a surface of the chip 30 , in contact with the surface of the chip 30. The phase change module is disposed on another surface of the chip 30 , opposite the metal-clad substrate 60 . A heat sink 40 is disposed on the side of the metal-clad substrate 60 facing away from the chip 30 . Heat generated by the chip 30 is carried away by the heat sink 40 through the metal-clad substrate 60 . The metal-clad substrate can be a three-layer substrate such as a direct bond copper (DBC) substrate, an active metal brazed copper (AMB) substrate (e.g., Al2O3-AMB, Si3N4-AMB, or AlN-AMB), or an insulated metal substrate (IMS). The upper and lower layers of the three-layer substrate are electrically conductive and thermally conductive materials. The lower layer, close to the power chip, provides a path for the flow of current within the power chip and allows for the timely removal of heat generated by the power chip. The upper layer, close to the heat sink, primarily provides protection for the power chip, reducing the impact of external impacts on the power chip. The middle layer is an insulating layer that prevents the conductive and thermally conductive material in the lower layer from conducting electricity to the heat sink, preventing problems such as short circuits in the chip. However, since the lower layer of a three-layer substrate, such as a DBC, is generally connected to the power chip using a copper layer, the relatively thin copper layer has limited effect on improving transient thermal performance, resulting in a small effective heat diffusion area and suboptimal steady-state thermal performance.

[0072] In some feasible embodiments, as shown in FIG9B , the phase change module is disposed between the chip 30 and the heat sink 40, and the metal-clad substrate 60 is disposed on the side of the phase change module facing away from the chip 30. Heat generated by the chip 30 is conducted to the metal-clad substrate 60 through the heat dissipation portion of the phase change module and ultimately carried away by the heat sink 40.

[0073] In a ninth embodiment, as shown in FIG10 , the power module further includes a plastic package 5, in which the chip 30, the phase change module, and the metal-clad substrate 60 are encapsulated. The chip 30, the phase change module, and the metal-clad substrate 60 are stacked in sequence. This uniform packaging method improves the overall structural integrity of the power module.

[0074] The power module can include multiple packaging methods. In some feasible implementations, the side of the chip 30 facing away from the phase change module is exposed on the outer surface of the plastic package 5, and the side of the chip 30 facing away from the phase change module is flush with the outer surface of the plastic package 5.

[0075] In some feasible embodiments, the power module also includes a plastic package 5, in which a chip 30 and a metal-clad substrate 60 are arranged. The chip 30 and the metal-clad substrate 60 are stacked, and the side of the metal-clad substrate 60 facing away from the chip 30 is used to set a heat sink 40. The phase change module is arranged outside the plastic package 5 and on the side of the chip 30 facing away from the metal-clad substrate 60.

[0076] In some feasible embodiments, which are not illustrated in the present application, the power module further includes a plastic package 5, in which a chip 30 is disposed. One side of the chip 30 in the thickness direction of the power module is used to set a heat sink 40, and the other side of the chip 30 in the thickness direction of the power module is used to set a phase change module.

[0077] In a tenth embodiment, as shown in FIG11 , the power module may include two chips, a chip 30 and a chip 30′, which are disposed on the same metal-clad substrate 60. A heat sink 40 is disposed on a side of the metal-clad substrate 60 facing away from the chip 30 and the chip 30′. In some feasible implementations, the chip 30 and the chip 30′ may be disposed on different metal-clad substrates.

[0078] In an eleventh embodiment, a power device is provided, comprising at least one power module and a circuit board as described in any of the above embodiments, wherein the power module is disposed on the circuit board, and the power device is configured for AC / DC conversion. The structure and operating principle of the power module in this embodiment can be referenced to the description of the above embodiments and will not be further elaborated in this embodiment.

[0079] Generally, the power device provided in the embodiment of the present application adopts the power module in the above embodiment. The above power module has a phase change module, which improves the thermal capacity of the power module, thereby improving the power module's resistance to junction temperature fluctuations. When the power is overloaded, the chip can still maintain a good uniform temperature, thereby improving the working performance of the power device when the power consumption is overloaded and improving stability.

[0080] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A power module, characterized in that: The power module comprises: a phase change module and a chip, wherein the phase change module and the chip are stacked; The phase change module comprises a containing frame and a phase change material, the containing frame comprises at least two containing cavities, the at least two containing cavities are arranged in sequence in a direction away from the first surface of the chip, and the phase change material is arranged in the at least two containing cavities; The at least two accommodating cavities include a first accommodating cavity and a second accommodating cavity, the distance between the first accommodating cavity and the chip is smaller than the distance between the second accommodating cavity and the chip, and the phase change point of the phase change material in the first accommodating cavity is higher than the phase change point of the phase change material in the second accommodating cavity, wherein the first surface of the chip is perpendicular to the thickness direction of the power module.

2. The power module according to claim 1, characterized in that: The at least two accommodating cavities are arranged in sequence along the thickness direction of the power module, and the plane where each of the accommodating cavities is located is parallel to the first surface of the chip, wherein the plane where the accommodating cavity is located is the plane where the surface of the accommodating cavity that is perpendicular to the thickness direction of the power module is located.

3. The power module according to claim 1, characterized in that: The at least two accommodating cavities are arranged in sequence along a first direction, and the plane where each of the accommodating cavities is located is perpendicular to the first surface of the chip, and the first direction is perpendicular to the thickness direction of the power module, wherein the plane where the accommodating cavity is located is the plane where the surface of the accommodating cavity that is perpendicular to the first direction is located.

4. The power module according to claim 3, characterized in that: Each of the at least two accommodating cavities is annular and is arranged in sequence from the center of the chip to the edge of the chip.

5. The power module according to any one of claims 1 to 4, characterized in that: The phase change module includes a first phase change module, the first phase change module is arranged on the first surface of the chip, the second surface of the chip is used to arrange a first heat sink, and the first surface is arranged opposite to the second surface.

6. The power module according to claim 5, characterized in that: The containing frame of the first phase change module includes a flow passage, which is used to provide a path for the current in the chip. The flow passage is arranged on a side of the containing frame of the first phase change module close to the chip, and the content of phase change material per unit volume in the flow passage is less than the content of phase change material per unit volume in other parts of the containing frame of the first phase change module.

7. The power module according to claim 6, characterized in that: No phase change material is arranged in the flow-through portion.

8. The power module according to any one of claims 1 to 7, characterized in that: The phase change module includes a second phase change module, and the second phase change module is arranged between the chip and the first heat sink; The accommodating frame of the second phase change module comprises a first heat dissipation portion and a first phase change portion, wherein the first phase change portion is arranged around the first heat dissipation portion, and a projection of the first heat dissipation portion on the thickness of the chip overlaps with the first surface of the chip; The content of the phase change material per unit volume in the first heat dissipation portion is smaller than the content of the phase change material per unit volume in the first phase change portion.

9. The power module according to claim 8, characterized in that: No phase change material is disposed in the first heat dissipation portion.

10. The power module according to any one of claims 5 to 9, characterized in that: A side of the first phase change module facing away from the chip is used to set a second heat sink; The accommodating frame of the first phase change module comprises a second heat dissipation portion and a second phase change portion, the second phase change portion is arranged around the second heat dissipation portion, and a projection of the second heat dissipation portion on the thickness of the chip overlaps with the first surface of the chip; A content of the phase change material per unit volume in the second heat dissipation portion is smaller than a content of the phase change material per unit volume in the second phase change portion.

11. The power module according to any one of claims 5 to 10, characterized in that: The projection of the first phase change module in the thickness direction of the power module covers the first surface of the chip.

12. The power module according to any one of claims 1 to 11, characterized in that: The power module comprises a metal-clad substrate, the metal-clad substrate is stacked with the chip and is in contact with a surface of the chip; or, The metal-clad substrate is disposed on a side of the phase change module away from the chip.

13. The power module according to any one of claims 1 to 12, characterized in that: The phase change frame is a metal frame or a diamond frame, and the phase change material is any one or more of a single metal, an alloy, an organic substance, and an inorganic salt.

14. A power device, characterized in that: The power device comprises at least one power module and a circuit board as described in any one of claims 1 to 13, and the power module is arranged on the circuit board.

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